Meeting China&#39;s Challenge, British Style(2)

This British shop is writing off simple, low-margin jobs, concentrating instead on tough-to-make parts in medium to high volumes for its new CNC multi-spindle machines.

Article Post: 9/1/2003

Ian Sheldon poses with the two Index MS32 CNC multi-spindle screw machines that are bringing more—and more challenging—business to Witon Engineering.

An important feature of the MS32 is its rounded front, which permits unprecedented access to the machining area to facilitate setups. The machine’s slide arrangement—two per spindle—permits the use of as many as 18 ID or OD tools.

Increasingly, Witon Engineering’s future is with difficult parts in challenging materials, such as these, produced on its CNC multi-spindle machines..

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Precision machining shops in the United States aren’t the only ones losing business to China and other low-wage countries. Shops in the United Kingdom are also taking a beating and, like us, looking for ways to stay competitive in the global marketplace.

Witon Engineering, a turned parts subcontractor in Barnstaple, United Kingdom, is confident that it has come up with a winning strategy. The firm has made a major investment in new CNC multi-spindle screw machines, which it is using to pursue mid- to high-volume jobs involving tighter tolerances, better surface finishes and difficult-to-machine materials.

The firm started in Wembley, England, just after the Second World War. It relocated to Barnstaple in 1970 and, 3 years later, bought its first Wickman multi-spindle cam automatic to complement its numerous Brown & Sharpe single-spindle cam automatics. Witon installed additional multi-spindle cam automatics later and soon became a leading supplier of parts to firms serving the auto industry.

Witon Engineering prospered until the 1990s when customers started sourcing parts overseas to take advantage of substantially lower prices made possible by lower labor costs. There as here, the flow of work out of the country has continued to increase to the point where many firms in the industry are struggling to survive. “I have been working in turned parts manufacture since 1963, and I have never seen such a high level of business being lost to overseas subcontractors,” reports Ian Sheldon, Witon’s owner and managing director. “It has been accelerating over the past 5 to 7 years. The emergence of reverse-auction bidding for major contracts has compressed profit margins still further.”

Mr. Sheldon realized in the mid-1990s that he could not compete against overseas firms for relatively simple parts made from easy-to-machine metals—in fact, much of that type of work had already been lost. He came to the conclusion that the only way his company could survive was to specialize in difficult parts made of more challenging metals, made on modern, more productive machines. He began purchasing single-spindle CNC lathes, both fixed-head and sliding-head, with multiple CNC axes and driven tooling, to complement the simpler CNC machines that the firm had been using since 1984.

Witon Engineering typically used its CNC single-spindle machines to produce runs of 1,000 pieces or more—the firm has always been interested in moderately high volumes. As the firm increasingly pursued jobs better suited to the capabilities of its CNC single-spindle machines, that is, jobs with very tight tolerances, good finish requirements and involving difficult-to-machine materials, it came on opportunities to produce medium to high volumes of such parts. Cycle times for producing the high-volume parts on the single-spindle machines were too high, however, and the firm explored the possibility of making them on a CNC multi-spindle machine.

The firm approached George Kingsbury, a U.K. distributor for Index-Werke GmbH, with a part it had been making on its CNC single-spindle machines in a cycle time of 72 seconds and asked how long it would take to make on an Index CNC multi-spindle. The distributor quoted 12 seconds to produce the part on the Index MS32 compact, CNC, six-spindle machine and backed up the quote with a demonstration. As a result, Witon Engineering purchased the machine in September 2002.

Features Of The Machine

An important feature of the MS32 Compact is that each of its six air-cooled spindle motors is completely independent. Good chip control, best surface finishes, short cycle times and longer tool life are achieved through optimum speeds at each spindle. The surface speed and spindle speed can be optimized for each cutting edge, even while in the cut, permitting the machining of materials that previously could not be machined on multi-spindle machines.

The arrangement of the tool slides without slide mounting blocks allows the use of more than one tool slide at each spindle, as seen in the close-up of the machining area (page 36). Ten of the machine’s twelve slides can be equipped as compound slides, and any of the ten can be equipped with ID or OD tools, independent of position. The tool mix can always be chosen optimally based on the needs of the particular job. Other features include the ability to use up to 18 tools including driven tools, the ability to do polygon turning and thread milling, and backworking with one or two tools. A distinguishing feature of the machine is its open front (photo on page 34)—Mr. Sheldon likens it the bow of a ship—that provides easy access for setups.

“This was our first CNC multi-axis machine, and I needed to personally work on it to see first-hand what it could do,” Mr. Sheldon explains. “I’ve never been more comfortable with a machine in terms of the way it’s laid out, its features and its capabilities.”

Another feature of the machine is the filtering system that removes particles of metal larger than 5 microns and prevents the coolant from becoming abrasive. This prolongs tool life, improves the accuracy of the machined component (15 microns total is routinely held) and extends the life of the machine itself. There is no need for tool presetting because datuming is performed within the machine; also, the tooling is repositioned for the next job by a global offset system. High-pressure through-tool coolant and the two two-axis slides at all but the first two stations assist in achieving short cycle times. Drills are hydraulically clamped thus held accurately on centerline, which is difficult if clamping is done on one side by means of a screw.

Synchronous pick-up at each of the six stations is by a chuck rather than a collet, allowing the part to be held rigidly for backworking, which is performed on most components at Witon Engineering even if it is just to deburr. All six main spindles have a full C axis. The temperature in the machine is held constant by a central refrigeration system. Mr. Sheldon is particularly impressed with the way that power is transmitted to the spindles by hard-wiring the electric supply instead of using rotary connectors. The wires are prevented from tangling by reversing the direction of motion after the fifth index to return the spindles to their original positions.

Integration of the bar feed, made by Iemca (St. Louis, Missouri), is described as seamless. Hexagonal as well as round bar is used, although Mr. Sheldon points out that polygon generation, even in stainless and alloy steels, is no problem because of the power and rigidity of the Index machine.

Mr Sheldon describes the (off-line) programming of the CNC multi-spindle as straightforward. “You program each spindle individually, and it’s very much like programming a two-axis lathe,” he explains. “It’s much easier than programming a multi-axis CNC machine, and there is not the potential for tool collisions that there is on a multi-axis machine.

“We did not buy the MS32 to do the jobs that were running on our cam automatic multi-spindles,” Mr. Sheldon emphasizes. “Our existing cam multi-spindles were (are) fine for the types of work they are used for. The Index machine is used for the more demanding jobs that we would otherwise have to run on our CNC single-spindle machines.”

Jobs are scheduled on the Index for reasons of part complexity or because they involve difficult-to-machine materials such as stainless steel. Mr. Sheldon feels that some of the machine’s features, such as the high-pressure, through-the-tool, coolant system, are particularly suited to machining stainless. Jobs are also grouped family-of-parts fashion to reduce setup time for changeovers. For example, the machine’s bar feed will accommodate bars ranging from, say, 7/8- to 1 1/8-inch diameter without an adjustment. Therefore jobs involving bar stock within that size range are grouped to avoid having to make an adjustment. Similarly, jobs involving parts with common features (same-size bores, threads, milled flats and so forth) are grouped to minimize tool changes.

Generates New Business

It did not take Witon Engineering long to find work for its new CNC multi-spindle. In one case, the shop received an order for 20,000 316 stainless steel threaded plugs with a broached hex socket. The customer had been having trouble getting quality parts elsewhere. He was also accustomed to getting parts a little at a time—1,000 one week, 1,500 the next, and so on. Witon Engineering was able to make the part complete (including the broaching operation) in one setup on the CNC multi-spindle and completed the 20,000-piece order in one week.

“The customer couldn’t get over getting the parts in so short a time,” Mr. Sheldon recalls. “He was not only pleased with the fast delivery, but also with the quality of the parts—a gleaming finish and very clean threads. He was so pleased, in fact, that he’s contracted to buy all of his brass and aluminum plugs from us as well—orders that will run into hundreds of thousand of parts.

“We previously made the stainless steel part for the customer on our CNC single-spindle machines,” Mr. Sheldon adds. “However, the part had a cycle time of about 65 seconds and, with our hourly rate, we couldn’t make the job pay. We’re currently running the part on the CNC multi-spindle with a cycle time of 12 seconds—more than five times faster.”

“We’re Busier”

With the installation of the CNC multi-spindle in September 2002, Witon Engineering started getting busier. By February 2003, the machine was booked to capacity, and it was obvious that the shop needed another, which it purchased. “Word has gotten around our industry in the U.K. that we have the machines, and inquiry levels are up substantially,” Mr. Sheldon reports. “We’re currently talking to two companies that are potentially major accounts—not just a few thousand parts per month, but families of parts that they are having trouble sourcing because of quality problems or capacity constraints. They’re very interested in giving us work for our Index machines.”

Mr. Sheldon’s firm continues to lose cam automatic work to China and other countries with lower labor costs. Labor costs in those countries are as little as one-thirtieth that in the U.K., he stresses. However, the decline in sales due to single- and multi-spindle cam automatic work that has gone overseas has been replaced by new business for the CNC multi-spindle machines. “Where less than 1 year ago we considered the Index machines as an additional form of production capacity, it’s now looking like it’s going to be a primary capacity,” Mr. Sheldon notes. “Our CNC multi business is gaining momentum. In hindsight, it’s been an excellent move.”

The CNC multi-spindles have proven to be advantageous in a number of ways. Although the U.K.’s economy is in a slump, the labor market is tight. Witon Engineering has had difficulty finding skilled operators for its cam automatics, especially for nights. On the other hand, the firm is finding it a lot easier to find setup people and operators for its two Index CNC machines. That has allowed the firm to run the machines virtually around the clock.

“Amortizing the cost of the machines over a 100-hour work week is much more advantageous than amortizing them over a 40-hour week,” Mr. Sheldon emphasizes. “The more hours you run, the less the hourly cost of the machine becomes an issue. It makes us a lot more flexible in the rates that we can quote our customers.”

Getting Into Fighting Shape

Witon Engineering is remaking itself as it adjusts to today’s competitive realities. The firm has eliminated 18 Brown & Sharpe single-spindle cam automatics and 10 of its multi-spindle cam automatics. At one time the firm had a secondary-operations department consisting of 15-16 personnel. With the firm’s transition to CNC single- and multi-spindle machines capable of producing parts complete in one setup, the secondary operations department has been reduced to 4 people.

With the move to CNC equipment, Witon Engineering has become a leaner, more efficient operation overall. The firm has downsized from 58 personnel to a staff of 40. Also, elimination of some of the cam automatics freed up a 6,000-square-foot unit that the firm previously occupied. It was able to rent out the space for additional income.

“We lost commodity parts like bolts and washers to overseas producers years ago,” Mr. Sheldon sums up. “Shops that continue to pursue jobs with fairly loose tolerances and easy-to-machine materials are going to be overwhelmed because those jobs can be made for a lot less overseas. We’ve got to move into markets where the tolerances are a little tighter, the materials are more difficult to machine, and the customers are a bit more demanding about deliveries—where they can’t wait for deliveries from China.”—LRR